AOSP is different from OEM builds. It's not an emulator problem, most of the time. The folks at Genymotion seem to be working on fixing that with preapproved builds and more powerful controls.
The acronyms don't really matter. What I need to know is that a bug encountered in the emulator would also occur on the devices and vice versa. If that doesn't happen then the emulator becomes yet another platform with a differing set of unique bugs.
Agreed. Unfortunately, that's a guarantee that Android's licensing model can't provide. Every manufacturer can do whatever they please, so fragmentation can't be regulated.